Open consultation

UK ETS: Scope expansion - emissions from international maritime voyages consultation (accessible webpage)

Published 25 November 2025

Introduction

The UK Emissions Trading Scheme (UK ETS) came into operation on 1 January 2021. The scheme is a key part of our approach to addressing climate change, setting a limit on emissions from the sectors covered and ensuring an appropriate price is applied to them. The scheme is jointly run by the UK ETS Authority (or ‘the Authority’), comprised of the UK Government, Scottish Government, Welsh Government and the Department of Agriculture, Environment and Rural Affairs for Northern Ireland.

In July 2023, following a consultation, the Authority confirmed its intention to expand the scope of the UK ETS to include emissions from domestic maritime from 2026 ^{[footnote 1]}. This was followed by a further consultation in November 2024 ^{[footnote 2]} on the technical details of implementation, as well as potential future expansion to additional maritime emissions.

The Authority confirmed some of the technical aspects of the scheme in an interim Authority Response ^{[footnote 3]}. This included the intention to expand the UK ETS to include emissions from international voyages. We set out further, full details of the expansion of the domestic scheme in the main Authority Response to the previous consultation, published alongside this document.

International maritime voyage emissions: context

In the UK Emissions Trading Scheme Scope Expansion: Maritime consultation, published in November 2024, we consulted on technical implementation details for how to expand the existing UK ETS scheme to include emissions from maritime. While the majority of the consultation focused on implementing the expansion of the scheme to domestic emissions, we also considered how a proportion of emissions from international voyages could be brought into this scheme in future.

In March 2025, the UK Government published the Maritime Decarbonisation Strategy ^{[footnote 4]}. This set out the pathway to a clean maritime future, required to deliver against the UK’s legally binding carbon budgets, providing certainty and clarity for the sector. The strategy focused on five key policies, one of which was placing a price on emissions from the maritime sector, such as through the UK ETS.

Since then there have been significant changes in the wider policy sphere, and in particular internationally. In October 2025, adoption of the IMO Net Zero Framework was delayed at the IMO Marine Environment Protection Committee. The UK was disappointed in this outcome and will continue to work with others to progress development of the IMO Net Zero Framework so that we can reach a position of consensus in the future. In our previous consultation, we committed to exploring how potential future inclusion of international emissions could work, should multilateral action through the IMO be delayed, or prove insufficient in reducing GHG emissions from international shipping.

Alongside this, in May 2025 the UK and EU agreed to work towards linking the UK Emissions Trading Scheme (UK ETS) and EU Emissions Trading System (EU ETS) at the UK-EU Summit. In the interim Authority Response published in July 2025, we set out that we intend to expand the UK ETS to include emissions from international maritime voyages, building on the Common Understanding ^{[footnote 5]} established at the summit which stated that both domestic and international maritime would be in scope of a linked scheme.

Given these events, this consultation sets out policy proposals on the expansion of UK ETS to include emissions for international maritime voyages.

Purpose of this consultation

As part of the November 2024 consultation, we included questions on the potential future inclusion of emissions from international maritime voyages. The majority of respondents were in favour and argued that this would ensure EU alignment, avoid carbon leakage and potential loopholes, incentivise decarbonisation, and demonstrate climate ambition. However, there were some concerns raised, including that the UK should wait to align with any measure agreed at the (then upcoming) April 2025 IMO Maritime Environment Protection Committee (MEPC) session. 

This consultation builds on the November 2024 consultation and outlines specific proposals for how we intend to expand the UK ETS to include emissions from international maritime voyages in line with the Common Understanding of May 2025 and the delay to adoption of the IMO Net Zero Framework.

Respondents need only reply to the questions that interest them or that they have views on. There is no requirement nor expectation to respond to every question in this consultation.

General information

Why we are consulting

Following agreement between the UK and the EU to work towards linking respective ETSs, the Authority is seeking input on proposals for expanding the UK ETS to include emissions from international maritime voyages. This consultation sets out proposals for how we intend to do this. In general, the proposals for expanding to international emissions are broadly in alignment with the EU ETS, particularly the emissions coverage. It seeks views on:

• How to expand to international voyages, including the emissions coverage.
• Whether the existing scope of the UK ETS maritime policy, or applicable regulation would need to change to allow for the international expansion.
• Adjusting the cap for the inclusion of emissions from international maritime voyages.
• A future review of the scheme, in light of the global measures developed at the IMO.
• Impacts of the scheme, including decarbonisation impacts and potential distributional impacts.

Consultation details

Issued: 25 November 2025
Respond by: 20 January 2026

Enquiries to:

Emissions Trading
Department for Energy Security and Net Zero 3rd Floor
3-8 Whitehall Place
London
SW1A 2EG

Email: ukets.consultationresponses@energysecurity.gov.uk

Consultation reference: UK Emissions Trading Scheme: Scope Expansion: Emissions from international maritime voyages

Audiences:

This consultation is expected to be of greatest interest to the shipping industry, non-governmental organisations (NGOs), academics and thinktanks.  

We also welcome the views of any individual or organisation that has an interest, directly or indirectly in the expansion of the UK ETS and/or the adjustment to the cap of the scheme.

We would like to hear your views on the proposed approach to expanding the scope of the UK ETS. We would like to know whether you think that the proposed policy changes are feasible in practice and will achieve our objectives.  

Territorial extent:

This consultation relates to proposals to develop the UK ETS, which operates across England, Scotland, Wales and Northern Ireland. This is a joint consultation, published by the UK Government, Scottish Government, Welsh Government and the Department of Agriculture, Environment and Rural Affairs for Northern Ireland.

How to respond

Respond online at: energygovuk.citizenspace.com/energy-markets/uk-ets-scope-international-maritime-emissions

or

Email to: ukets.consultationresponses@energysecurity.gov.uk

Write to:

Emissions Trading
Department for Energy Security and Net Zero
3rd Floor
3-8 Whitehall Place
London
SW1A 2EG  

When responding, please state whether you are responding as an individual or representing the views of an organisation.

Your response will be most useful if it is framed in direct response to the questions posed, though further comments and evidence are also welcome.

Confidentiality and data protection

Information you provide in response to this consultation, including personal information, may be disclosed in accordance with UK legislation (the Freedom of Information Act 2000, the Data Protection Act 2018 and the Environmental Information Regulations 2004).

Consultation responses will be shared across the UK ETS Authority.

If you want the information that you provide to be treated as confidential, please tell us, but be aware that we cannot guarantee confidentiality in all circumstances. An automatic confidentiality disclaimer generated by your IT system will not be regarded by us as a confidentiality request.

We will process your personal data in accordance with all applicable data protection laws. See our privacy policy.

We will summarise all responses and publish this summary on GOV.UK. The summary will include a list of names or organisations that responded, but not people’s personal names, addresses or other contact details.

Quality assurance

This consultation has been carried out in accordance with the government’s consultation principles.

If you have any complaints about the way this consultation has been conducted, please email: bru@energysecurity.gov.uk.

Summary of Proposals

Expansion to International Maritime Voyages Proposal

The UK ETS Authority is consulting on including emissions from international maritime voyages starting or ending in the UK. We propose that this expansion should take place from 2028. We also intend that international voyages are only subject to the UK ETS carbon price for 50% of their emissions, in line with the current EU ETS scope.

We propose that the expansion to international voyages would apply to ships which will already be in scope of the UK ETS because of their domestic voyages or emissions in ports ^{[footnote 6]} in the UK and would cover the same greenhouse gases. These have been set out in the interim and main Authority Response to the UK Emissions Trading Scheme Scope Expansion: Maritime consultation.

What is the current scope of maritime in the UK ETS?

From July 2026, the scope of the UK ETS will be as follows:

• Ships of 5000 gross tonnage and above performing eligible maritime activity.
• In general, government maritime activity will be exempt from the UK ETS. This will include military activities, customs and Border Force activities, police activities, coastguard and other search & rescue activity, emergency medical ships, government research activities, and General Lighthouse Authority activity.
• There are additional exemptions for ferries serving Scotland’s island and peninsula communities, and for fish-catching and fish-processing ships, to be reviewed in 2028.
• Offshore ships will be included in the scheme from January 2027.
• Coverage of carbon dioxide, methane and nitrous oxide.

Scope of the Proposal

We propose that an international voyage in scope of these proposals would be a voyage in either direction between a UK port and a port outside of the UK. We also propose that emissions from voyages to and from Crown Dependencies and Overseas Territories are to be captured under these proposals. As outlined in previous consultations and in the main Authority Response, we consider that there should be a high bar for any exemptions from the UK ETS. We are keen to gather stakeholder views on this approach through the consultation, including evidence of the impacts on these communities. 

In practice, we propose that participants would monitor and report 100% of their greenhouse gas emissions on a voyage between a UK port and a port outside of the UK. However, operators would only be required to surrender allowances to cover 50% of their emissions. In addition to this, participants would be required to surrender allowances for 100% of their emissions while in port in the UK, as already confirmed in the interim Authority Response, published in July 2025.

The UK is committed to free and open trade, our domestic and international climate change commitments, and the needs of industry and consumers. Upholding the United Nations Convention on the Law of the Sea (UNCLOS) as the legal framework for all activities in the ocean and seas underpins all aspects of the UK’s ocean policy. Therefore, we will ensure that any measures taken forward are in compliance with our international obligations, including our rights and obligations under UNCLOS, our commitments under the World Trade Organisation and trade agreements, and climate treaties including the UNFCCC and the Paris Agreement.

Based on estimates from the DfT’s maritime emissions model, in 2019, the UK’s share of international maritime voyage emissions ^{[footnote 7]} was approximately 7.5MtCO2e on a tank-to-wake basis. Of these emissions, it is estimated approximately 6.9MtCO2e (92%) were produced by ships over 5000GT and would be brought into scope of the UK ETS, subject to any exemptions. Given all in-port emissions including those from ships on international voyages are included within the scope of domestic maritime scheme, all emissions brought into scope under this expansion would be emissions produced during voyages.

For ships over 5000GT, it is estimated that approximately 3.5MtCO2e were emitted on voyages between the UK and the EEA, and 3.4MtCO2e on voyages between the UK and the Rest of the World ^{[footnote 8]}. Container ships (1.74MtCO2e), ro-pax ferries (0.96MtCO2e), and oil tankers (0.88MtCO2e) were the vessel types estimated to make the largest contribution to the UK’s share of international maritime voyage emissions.

Whilst a vote on adoption of the IMO’s Net Zero Framework (NZF) has been delayed, the UK will continue to work with others to progress its development, and adoption. Once adopted it is expected to cover the emissions from ships 5000GT and above that performed any international voyages in a given year. This includes domestic emissions from vessels that performed a mix of domestic (UK-UK port voyages) and international (UK-international port voyages). We will review the coverage of maritime emissions in UK ETS following adoption of the NZF.

Implications for GB-NI Routes

We have previously consulted on two options to overcome the disparity in carbon pricing obligations on routes between Northern Ireland and Great Britain, and the Republic of Ireland and Great Britain, due to differing emissions coverage by the EU ETS and UK ETS. The main Authority Response outlines that to ensure carbon pricing equivalence on these routes, the UK ETS Authority will provide a 50% surrender deduction for voyages between Northern Ireland and Great Britain, from implementation in July 2026.

The main Authority Response stated that this measure will only remain in place for as long as the disparity remains. This means the 50% surrender deduction for routes between Northern Ireland and Great Britain will no longer apply from the point at which international voyages are brought into the UK ETS, which is proposed to be 2028. This will mean that a 100% surrender obligation will apply for voyages between Northern Ireland and Great Britain after this point.

Implications for the scope of the scheme

As set out in the main Authority Response, we are going to provide further information for offshore ships in guidance and legislation. For the purposes of this consultation, we propose that a surrender obligation will also apply to offshore ships for 50% of their greenhouse gas emissions from international voyages.

Through this consultation, the UK ETS Authority is interested to understand whether the scope of the scheme, as outlined in the main Authority Response, would need to be amended if proceeding with the expansion to include emissions from international voyages. For example, we acknowledge the EU ETS ice class vessel policy which allows such ships to surrender 5% fewer allowances until 31 December 2030. At this stage, we are not intending to introduce a similar reduction in surrender allowance for the UK ETS. However, we are interested in gathering views on whether some adjustments need to be made for ice class ships, or for any other ship types in an international context.

Implications for regulatory provisions

Finally, we would also be interested to understand whether any of the regulatory provisions set out in the main Authority Response would need to change in response to proposals to extend the UK ETS to include emissions from international voyages. For example, in the main Authority Response, we set out that we will remove the requirement for a Document of Compliance for the domestic expansion. This is because compliance with the UK ETS will be managed by the UK ETS regulators via the Manage your Emissions Trading Scheme (METS) system and the UK Emissions Trading Registry.

Through this consultation, we would be keen to understand whether that approach would need to change if expanding the UK ETS to include emissions for international journeys. We are also aware that other regional schemes, such as the EU ETS, contain further powers for enforcement including powers of expulsion and port bans. We are keen to understand whether stakeholders consider such powers would be beneficial in the enforcement of the scheme. We would also welcome any other views on further suggested regulatory changes.

Questions

1. Do you agree with our proposal to include 50% of emissions from international voyages within the UK ETS from 1 January 2028? (Y/N) Please explain your response, providing evidence where possible.

2. Do you think that the emissions from voyages to and from Crown Dependencies and Overseas Territories should be included in the scope of the scheme? (Y/N) Will it lead to any gaming, avoidance or adverse impacts if they were exempted? Please explain your response, providing evidence where possible.

3. Do you agree that offshore ships should be included in the scope of the expanded scheme? (Y/N) Will it lead to any gaming, avoidance or adverse impacts? Please explain your response, providing evidence where possible.

4. Do you agree with the intention to not provide a 5% reduction in allowance surrender for ice class vessels? (Y/N) Please explain your response, providing evidence where possible.

5. Does the scope of the scheme as outlined in the main Authority Response need to be further amended in light of proposals to include international voyages? (Y/N) Please explain your response, providing evidence where possible.

6. Do the regulatory provisions as outlined in the main Authority Response need to change in light of proposals to include international voyages? For example, does the requirement for a Document of Compliance need to be reinstated, or further regulatory powers such as port bans or expulsion need to be added? (Y/N) Please explain your response, providing evidence where possible.

Cap adjustment

In the main Authority Response, we confirmed that we will adjust the cap to account for the expansion of the ETS to domestic maritime. The number of allowances that will be added is in line with the UK Government’s Maritime Decarbonisation Strategy and its net zero consistent trajectory for domestic maritime.

This reflected our proposal in the consultation and is consistent with the principle supported by stakeholders in the previous consultation that scope expansion should generally be accompanied by a corresponding adjustment to the cap.

As outlined in the main response, the Authority noted the Climate Change Committee’s (CCC) recommendation to not adjust the cap when domestic maritime is added to the UK ETS. However, following the CCC’s advice, the Authority reevaluated the current UK ETS cap trajectory to test its net zero consistency and found there was no material change in the underlying assumptions that informed the original net zero consistent cap trajectory. As such, the Authority believed there was limited justification for reopening the cap position agreed as part of the Developing the UK ETS consultation response.

The Authority proposes following a similar approach for expanding the UK ETS to include emissions from international voyages. We are therefore minded to adjust the cap using the latest net zero-consistent trajectory for emissions from international voyages, as set out in the Maritime Decarbonisation Strategy ^{[footnote 9]}. This will ensure that the overall UK ETS cap remains net zero consistent and continues to support the delivery of the UK’s climate targets.

The Authority has decided to extend the UK ETS into a Phase II from 2031 onwards, and we will seek to consult on a specific Phase II cap trajectory as soon as possible. Any Phase II cap trajectory will need to align with cross-economy decarbonisation plans across all four nations. The Authority believes the cap adjustment will preserve scheme credibility and ensure consistency with the policy intent of the emissions trading scheme, promoting cost-effective decarbonisation.

Table 1: Indicative cap adjustment figures for UK ETS scope expansion to international maritime voyages under Phase I cap (2028-2030).

Year	Annual GHG Emissions Added to UK ETS Scope from 50% international maritime voyage inclusion (Tank-to-Wake, MtCO₂e)
2028	5.0
2029	4.9
2030	4.7

The figures presented for emissions coverage under a 50% international voyage scope expansion are indicative only and do not reflect a finalised policy position. They are based on modelling from the Maritime Decarbonisation Strategy (MDS) published in early 2025 and are subject to change as policy and modelling evolve. These estimates are intended to provide a sense of scale for potential cap adjustments in Phase I of the scheme (which runs to the end of the scheme year beginning 1 January 2030), under the existing legislated UK ETS cap. Future updates to modelling may result in revised figures, and any final policy decisions will be informed by further analysis and consultation.

Questions

7. Do you agree with our proposal to adjust the cap using the net zero consistent trajectory as set out in the more up to date published trajectory at the point of the Authority Response to this consultation? (Y/N) Please explain your response, providing evidence where possible.

Future Review

The IMO Net Zero Framework (NZF) once adopted will help to incentivise ships to transition to cleaner fuels, with revenues kickstarting the sector’s transition to green fuels and technologies, and promoting a just and equitable transition in developing countries, in particular Least Developed Countries and Small Island Developing States. 

Whilst the UK will work with others to progress the development and adoption of the NZF, the recent delay to adoption means that there is a need for immediate action to be taken to drive forward global maritime decarbonisation efforts. 

We recognise stakeholders have concerns about additional administrative burden for operators  and we are keen to minimise this.  In doing so, we aim to create effective and coherent measures that deliver investor certainty and tangible progress to decarbonise the maritime sector.     

The EU has committed to review the approach to the EU ETS for maritime, following adoption of the NZF ^{[footnote 10]}. This includes legislative proposals to examine the need to apply the allocation of allowances and surrender requirements to more than fifty percent (50%) of the emissions from ships performing international voyages, and is due to be issued within 18 months of the NZF adoption.  

Following adoption of the IMO NZF we will review the interaction of the UK ETS and the IMO NZF, and will explore the options for managing any future interactions, including reviewing any future changes to the EU ETS.  

Questions

8. What measures should the UK Government undertake to ensure that both the UK ETS and the IMO’s Net Zero Framework, following adoption, can effectively support the decarbonisation of the UK maritime sector? Please provide supporting evidence for your views, including costs and benefits.

Impacts

The inclusion of 50% of emissions from international voyages is expected to be a significant driver for decarbonisation. It will ensure that 100% of emissions are covered on voyages between the UK and the European Economic Area (EEA), from the combination of the UK ETS and EU ETS. The additional 50% of emissions coverage on other international routes will support the decarbonisation of these routes. Impacts associated with this policy will be analysed as part of the Impact Assessment (IA) to be published alongside the Authority Response to this consultation.

Potential impacts of UK ETS expansion to international maritime voyages

The Impact Assessment ^{[footnote 11]} accompanying the main Authority Response on the expansion of the UK ETS to domestic maritime sets out the evidence on the expected impacts of domestic expansion. Benefits include greenhouse gas emissions savings and air quality benefits in the maritime sector, whilst costs include costs to maritime operators of investing in abatement technologies, administrative costs to operators of complying with the scheme, and the cost of buying UK ETS allowances. The proposed expansion of the scheme to UK international maritime voyages is expected to deliver similar impacts on greenhouse gas emissions savings and air quality benefits. However, the precise extent of this is uncertain, in part due to interactions between the UK ETS and EU ETS, and interactions between these schemes and the IMO NZF, which will both be subject to review following adoption of the IMO NZF to account for these interactions.

As the expansion to domestic maritime emissions includes all emissions produced in port domestically, regardless of the voyage, the proposed expansion to international maritime voyages would not bring any new maritime operators into scope. In addition, many operators will also be subject to EU ETS and IMO Data Collection System (DCS) requirements. Therefore, additional administrative costs from expansion to international maritime voyages are expected to be minimal. However, operators conducting both domestic and international voyages will see a greater proportion of their emissions covered by the UK ETS, which may increase their overall abatement and allowance purchasing costs.

Early evidence from the EU ETS expansion to maritime shows that there is limited evidence of route changes to avoid ETS coverage, however, there is some evidence of ships making additional ports of call in the UK to avoid paying full coverage on intra-European journeys ^{[footnote 12]}. By expanding the UK ETS to cover 50% of international voyage emissions, this would remove the incentive for vessel operators to undertake additional ports of call in the UK, therefore reducing the risk of gaming and carbon leakage, though this could result in lower UK port activity.

Other evidence from the same EU report ^{[footnote 13]} has shown that the additional costs imposed by the EU ETS on the transportation of goods via maritime are expected to be low, however, maritime operators have begun to implement surcharges to cover and pass-through these costs. The extent to which ETS costs are passed through to the final costs of goods is uncertain, but is expected to be minimal based on existing evidence, which is set out in the Impact Assessment for domestic maritime expansion. Further evidence on the potential impact of the expansion of the ETS to domestic maritime is explored in the Impact Assessment. This evidence is broadly expected to also apply for the expansion to international maritime voyages. However, there may be some impacts that are of greater relevance to UK - international maritime voyage expansion, for example, impacts on international trade, and risks of modal shift from maritime to modes of transport not covered by the UK ETS.

Questions

9. Do you agree with our understanding of the impacts of including international voyages in the UK ETS? (Y/N) Please explain your response, providing evidence where possible.

10. Do you think that the proposed expansion to international maritime voyages could lead to any adverse impacts? (Y/N) This could include, but is not limited to, impacts on prices and availability of goods for consumers, impacts on the competitiveness of the UK maritime sector, impacts on supply chains, shift to other transport modes, or trade impacts. Please explain your response, providing evidence where possible.

11. Do you think we need to take any action against gaming, transhipment, or evasion if the UK ETS extends to cover emissions from international maritime voyages? (Y/N) Please explain your response, providing evidence where possible

12. Would changes to the global carbon pricing landscape (e.g. the IMO NZF or EU ETS) affect the impacts of the proposed UK ETS expansion to international maritime voyages? If so, how?

Welsh language impacts

The Welsh language is a strategic priority for the Welsh Government. Its Welsh Language Strategy, Cymraeg 2050: A million Welsh speakers, has two overarching targets: to reach a million Welsh speakers and to double the percentage of us that use Welsh every day by 2050.

The strategy is delivered across Welsh Government, spanning various policy areas such as housing, the economy, agriculture and education. As such, it is important that we assess the potential effects of proposed policy solutions on the Welsh language and the delivery of our Welsh Language Strategy. We would like your views on how any proposed changes in relation to expanding the scope of the ETS to include international maritime voyages could support our efforts to increase the number of people who speak and use Welsh, avoid any negative impacts, and ensure that we support the delivery of the Welsh Language Strategy.

Question

13. What, in your opinion, would be the likely effects of increasing the scope of the UK ETS to include international maritime voyages on the Welsh language?  We are particularly interested in any likely effects on opportunities to use the Welsh language and on not treating the Welsh language less favourably than English.

a. Do you think that there are opportunities to promote any positive effects?

b. Do you think that there are opportunities to mitigate any adverse effects?

14. In your opinion, could increasing the scope of the UK ETS to include international maritime voyages be formulated or changed so as to:

a. have positive effects or more positive effects on using the Welsh language and on not treating the Welsh language less favourably than English; or

b. mitigate any negative effects on using the Welsh language and on not treating the Welsh language less favourably than English?

Next steps

The responses to this consultation will be used to develop final policy decisions regarding the expansion of the UK ETS to include emissions from international maritime voyages.

The consultation will be open for 8 weeks before closing. The Authority will then work through the responses and aim to publish the Authority Response in due course.  

1. GOV.UK: Developing the UK Emissions Trading Scheme (UK ETS). ↩

2. UK ETS scope expansion: maritime sector. ↩

3. UK ETS scope expansion: maritime - interim response. ↩

4. GOV.UK: Maritime decarbonisation strategy ↩

5. GOV.UK: UK-EU Summit - Common Understanding (HTML). ↩

6. ‘In-port emissions’ constitute emissions at berth in UK ports and emissions from movements within UK ports. ↩

7. The UK’s share of international maritime voyage emissions is defined as 50% of emissions from all journeys between a UK port (or an offshore installation in the UK’s EEZ) and a port in another country, excluding any emissions produced in port. ↩

8. The remaining 0.05MtCO2e were produced on voyages between the UK and an unknown port. Journeys where either the start or end port of call are unknown occur when the ship is in transit at the start or end of the year. ↩

9. GOV.UK: Maritime decarbonisation strategy. ↩

10. Directive - 2023/959 - EN - EUR-Lex. ↩

11. UK ETS scope expansion: maritime sector. ↩

12. Monitoring of the implementation of Directive 2003/87/EC in relation to maritime. ↩

13. See link in footnote 12. ↩